→ The affected gene is located on the X-chromosome. Females have two versions of this chromosome while males only have one. Males with this variant are affected by AIS. Females can be carriers of this variant (heterozygous, X/Xais).

Possible Genotypes:

Genotype

The horse is:

Effects:

X/X

a normal female.

The mare has no genetic variant causative for the AIS and therefore cannot pass it on to its offspring.

X/Xais

a carrier female.

The mare is clinically healthy. The genetic variant will be passed on to its offspring with a probability of 50%. If the variant is passed on to male offspring, the foal will be an affected male.

X/Y

a normal male.

The male has no genetic variant causative for the AIS.

Xais/Y

an affected male.

The male appears to be a normal female but has the male genotype (XY) and is infertile.

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Recommendations:

Offspring of a carrier female should be tested for their genotype (X/X or X/Xais or Xais/Y → affected male).

Carrier females (X/Xais) may be used for breeding but their male offspring have a 50% of being affected.

Affected males (Xais/Y) are infertile but otherwise healthy.

Test information: This test detects the single basepair change in the AR gene.